Israeli president, Shimon Peres (left), greets the US vice-president, Joe Biden, in Jerusalem, where a new round of peace talks with the Palestinians has been agreed. Photograph: Israeli government/EPA

The US vice-president, Joe Biden, promised the Israeli government today that it had the strong support of Washington and said the US was committed to preventing Iran from obtaining nuclear weapons.

"There is no space between the US and Israel when it comes to Israel's security," Biden said, after meeting the Israeli prime minister, Binyamin Netanyahu, in Jerusalem. Their talks appeared to focus on Iran and its nuclear ambitions, rather than on the new round of low-key, indirect peace talks between Israel and the Palestinians that was agreed yesterday.

Biden, who is the most senior US official to visit Israel since Barack Obama was elected last year, said addressing Iran's nuclear programme was a priority. "We are determined to prevent Iran from acquiring nuclear weapons," he said.

In private he is also believed to have cautioned the Israeli government against any unilateral military strike on Iran, and to have tried to win Israeli support for the US administration's policy, which is moving towards sanctions against Iran.

Earlier, before a meeting with the Israeli president, Shimon Peres, Biden said Iran had become more isolated since the Obama administration came to power.

Netanyahu made clear today the Israeli government hoped for a tougher sanctions regime against Iran. "The stronger those sanctions are, the more likely it will be that the Iranian regime will have to chose between advancing its nuclear programme and advancing the future of its own permanence," he said.

Netanyahu frequently cites the need to address Iran's nuclear ambitions as his priority in government and Israeli leaders have pointedly not ruled out a military option.

Biden, who was later due to meet the Palestinian president, Mahmoud Abbas, repeated the US goal for a two-state peace agreement that would see the creation of an independent Palestinian state alongside Israel.

Yesterday, the US special envoy, George Mitchell, announced that Israel and the Palestinians had agreed to new, indirect talks, although discussion on the "structure and the scope" was only beginning.

The peace process has been under way for nearly two decades, but there have been no direct negotiations between the two since Israel's war in Gaza a year ago. Few on either side hold out much hope for the new "proximity talks".

Just before the announcement, the Israeli defence ministry said it had authorised the construction of 112 apartments in the Jewish settlement of Beitar Illit, on the occupied West Bank. That came despite a temporary, partial curb on settlement building announced by Netanyahu last November.

The Palestinians have insisted there would be no return to direct talks unless there was a full halt to Israeli settlement construction, in line with the obligations of the US road map. All settlements on occupied territory are illegal under international law.